This invention relates to fire event sensing devices and, more particularly, to a system for automatically monitoring the operability of fire event sensors housed within a fire event detection unit.
Although the percentage of U.S. households having at least one fire detection device of some type has grown to over 92%, the percentage of deaths caused by residential fires has remained steady. The fact that approximately one-third of all fire detection devices are non-operational when needed is a key reason for this unfortunate statistic. A large number of fire-related incidents involving property damage, personal injury, or even death are attributable to malfunctioning fire detection units. Malfunctioning smoke, heat, carbon monoxide, or other fire event sensors, or even dead or disconnected batteries, are often the result of a lack of manual testing by residents. It is therefore desirable to have a system for automatically and continuously testing the operability of sensors housed within a fire detection unit whether they are smoke, heat, carbon monoxide or other fire event sensors.
Several methods and devices have been proposed to monitor the operability of various fire event sensing devices. In U.S. Pat. No. 4,595,914 to Siegel, a self-test circuit for a fire event detector is disclosed for automatically periodically testing whether the sensitivity of an ionization-type sensor is within a certain predetermined range. A fire event smoke alarm which automatically periodically tests the detector""s operation or periodically sounds the detector""s alarm to remind the occupant to manually test the alarm is disclosed in U.S. Pat. No. 4,965,556 to Brodecki. The prior art further includes several methods and devices for manually checking the functionality of combustion detection circuitry. In addition, U.S. Pat. No. 5,619,184 to Torikoshi discloses a system for disaster prevention having a sensor, a CPU, and a memory for comparing sensor data with stored data.
Although assumably effective in operation, such known methods and devices are incapable of monitoring the integrity and functionality of multiple types of fire event sensors housed within a single detection unit. In addition, the above referenced devices only provide a single test of integrity or operability, such as simulating a fire event within a predetermined fixed range of sensitivity or merely detecting whether any signal is received from a sensor. Significantly, the acceptable range of sensor sensitivity, actions to be taken based on self-test results, and the frequency of periodic checking can not be modified or adjusted without the replacement or addition of new circuitry. Further, the referenced devices do not allow the residential occupant to verify that the self-checking circuitry itself is functioning properly.
It is therefore desirable to have a system which automatically checks the integrity and operability of fire event sensors and power supply housed within a fire detection unit according to predetermined and modifiable parameters.
In response thereto I have invented a system which automatically checks the integrity and operability of fire event sensors housed within a fire detection unit. The system disclosed herein utilizes a programmable master logic circuit which compares data received from each sensor with multiple predetermined parameters, such as acceptable time duration between sensor readings, existence of signal, acceptable sensor sensitivity, strength of battery power, threshold levels of logical readings, and other parameters. The master logic circuit can be reprogrammed with a different set of parameters without the need for additional circuitry. The system further provides for manual testing of the integrity of the circuitry and monitors the operability of the sensor monitoring routine itself. An audible and/or visual alarm is activated if any of the predetermined operability parameters are violated, thus indicating a malfunction. The system further provides for manual resetting of all sensors following a fault caused by any sensor.
It is therefore a general object of this invention to provide a system for monitoring the operability of fire event sensors which automatically tests the operability of each sensor.
Another object of this invention is to provide a system for monitoring the operability of fire event sensors which continuously tests the operability of each sensor.
Yet another object of this invention is to provide a system for monitoring the operability of fire event sensors having a programmable logic circuit which monitors a sensor""s operability according to a plurality of parameters for determining if each sensor is operating correctly.
A further object of this invention is to provide a system for monitoring the operability of fire event sensors having a logic circuit that may be reprogrammed with a different set of parameters and associated logic without the addition of new circuitry.
A still further object of this invention is to provide a system for monitoring the operability of fire event sensors having a means for manually testing the integrity of all circuitry.
Another object of this invention is to provide a system for monitoring the operability of fire event sensors having a means for monitoring the operability of the sensor monitoring system itself.
A further object of this invention is to provide a system for monitoring the operability of fire event sensors which can manually reset an alarm or sensors following activation.
A still further object of this invention is to provide a system for monitoring the operability of fire event sensors which sounds an audible and/or visual alarm when at least one fire event sensor or a battery is malfunctioning.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, embodiments of this invention.